The medical or veterinary use of syringes and other needle bearing devices involves a well-defined risk of accidental contact with the needle, a so-called needle-stick injury. In many cases (e.g., HIV), such needle-stick injuries can have deadly implications. In one published needle-stick injury study, the characteristics of needle-stick injuries caused by various needle bearing devices was analyzed. Of 326 injuries occurring over a ten month period (almost 33 incidents per month), disposable syringes accounted for 35 percent, all intravenous devices accounted for 35 percent, prefilled cartridge syringes accounted for 12 percent, phlebotomy needles accounted for 5 percent, and other devices accounted for 13 percent thereof. See, Jagger et al., New England Journal of Medicine, 319: 284-288 (1988).
One commercially available disposable syringe is illustrated in FIGS. 1A-1F. This syringe is Becton-Dickinson Company's Plastipak.RTM. Luer-Lok.RTM. syringe. As illustrated, plastic non-shielded disposable syringes generally have few parts. The plastic plunger 10 is provided with a rubber plunger tip 12 and in combination these elements form the plunger assembly which creates the necessary pressure to draw and/or expel fluids into or from the syringe barrel 14. The tip of the plastic syringe barrel 15 is typically shaped to accept a needle and hub combination 16, sometimes referred to as the needle assembly. In many disposable syringes the fit of the needle assembly on the tip of the syringe barrel is by friction. In other cases, some locking means may be employed, e.g., twist action, screw action, etc. Finally, in most disposable plastic syringes commercially available today, the needle assembly is further provided with a plastic needle guard 18 which fits over the needle prior to use, and which may be employed after use to prevent accidental needle-stick injuries after the disposed of syringe. In most cases, the attachment of the needle guard 18 over the needle assembly is by friction fit, but other attachment means may also be employed, e.g., twist action, snap lock, screw action, and the like.
In syringes of the FIGS. 1A-1F type, there is an obvious needle-stick danger associated with the act of reattaching the needle guard to a used needle, and this why such syringes are becoming less and less popular. As reported by Jagger et al., supra, the recapping of disposable syringes was the most common mechanism of needle-stick injuries for such devices. Recapping accidents typically occurred in three ways; (1) the cap was missed entirely; (2) the needle pierced a cap that was too short; and (3) the cap fell off of the needle after disposal.
The U.S. Department of Labor, through the Occupational Safety and Health Administration (OSHA) in compliance directive CPL 2-2.44B, Enforcement Procedures for Occupational Exposure to Hepatitis B Virus and Human Immunodeficiency Virus, expressly prohibits the recapping of used needles and other sharp instruments by hand.
Improvements in syringe designs, particularly safety syringes where the syringe itself is provided with means specifically designed to reduce or eliminate accidental needle-sticks and/or unauthorized reuse of the syringe, are thus in great demand.
Two safety syringes currently being marketed are the Becton-Dickinson Co. Safety-Lok.TM. syringe and the Sherwood Medical Co. Monoject.RTM. safety syringe. These syringes are both sleeve-type safety syringes, wherein a sleeve located around the syringe barrel, can be extended over the needle area to prevent accidental needle-stick injuries.
In each case, the sleeve is slidably attached to the syringe barrel, with a locking means at the needle end thereof. Before use, the sleeve is positioned rearwardly, so that the needle is exposed and available for use. After use, and prior to safe disposal, the sleeve is extended in a forward manner, over the exposed needle, and it is locked in place. While these two devices solve several of the needle-stick problems presently faced by users of such devices, they do not prevent the reuse of the syringe by others, nor do they provide all of the other advantages associated with the improvements in such designs as taught herein.
These two commercially available syringes are illustrated in FIGS. 2A-2I and 3A-3K attached hereto.
Many of the components employed in the FIGS. 2A-2I device are also present in the FIGS. 1A-1F syringe, since the two syringes originate from a common source, the Becton-Dickinson Company (B-D). The FIGS. 2A-2I syringe is B-D's Safety-Lok syringe. As in the FIGS. 1A-1F syringe, the FIGS. 2A-2F plunger 10 is provided with a plunger tip 12, and the syringe further includes a barrel 14. As before, the tip of the syringe barrel 15 is shaped to accept the needle and hub combination 16, sometimes referred to as the needle assembly. The needle assembly 16 is further provided with a needle guard 18 which sits over the needle prior to use. As in the previously described syringe, the attachment of the needle guard 18 over the needle assembly is by friction fit. This needle guard however, is not intended to be reused.
The unique components of the FIGS. 2A-2I syringe are the barrel locking ring 20, which fits over the tip of the syringe barrel 15 and may be used to lock the needle assembly 16 thereto, and the needle shield 22, which slidably fits around the periphery of the syringe barrel 14 and which has locking means 24 at the rear end thereof.
When positioned over the periphery of the syringe barrel 14, the shield 22, in its use position is essentially contiguous with the barrel 14, and the needle assembly is substantially exposed. After use, the shield 22 is pushed forward, over the needle assembly 14 until the locking means 24 mates with locking ring 20 located at the tip of the barrel. In this position, the syringe may be safely disposed of.
One drawback of this design is that the locking mechanism is not permanent, i.e., the locked shield may readily be unlocked, and the syringe could be reused by an unauthorized party. More importantly, should the safety shield become disengaged before or after disposal, the risk of accidental needle-stick injury is no different than with the unshielded syringe design. The syringe design of the present invention attempts to solve these deficiencies.
Another commercially available shielded syringe is illustrated in FIGS. 3A-3K. This syringe is available as the Monoject.RTM. safety syringe from the Sherwood Medical Company. As in the previously described syringes, many of the components are common including the plunger 10, which is provided with a plunger tip 12, the syringe barrel 14 and needle assembly 16, and finally the needle guard 18. As with the previously described shielded syringe, the needle assembly is further provided with a needle guard 18 which sits over the needle prior to use. As in the previously described syringes, the attachment of the needle guard 18 over the needle assembly is by friction fit, and as in the previous shielded design, this needle guard is not intended to be reused.
The unique components of the FIGS. 3A-3K syringe are akin to those used in B-D's Safety-Lok syringe (FIGS. 2A-2I) and include a barrel locking ring 20, which fits over the tip of the syringe barrel 15 and may be used to lock the needle assembly 16 thereto, a slidable needle shield 22, which fits around the periphery of the syringe barrel 14 and which has locking means 24 at the rear end thereof. Finally, the front end of the safety shield, there is provided a restrictive collar 25, which effectively prevents finger contact with the needle when the safety shield is extended.
When positioned over the periphery of the syringe barrel 14, the shield 22, in its use position is essentially contiguous with the barrel 14, and the needle assembly is substantially exposed. Unlike the B-D Safety-Lok.TM. safety syringe, the Monoject.RTM. safety syringe further includes positive shield stops (not shown) in both the extended and retracted positions to prevent accidental movement of the shield while drawing medication, giving an injection, transporting the filled syringe, or discarding the used syringe. After use, the shield 22 is pushed forward, over the needle assembly 14 until the locking means 24 mates with locking ring 20 located at the tip of the barrel. A two-step locking mechanism is employed in the Monoject.RTM. safety syringe. In the first position, the shield may be retracted. In the second position, the stop mechanism is designed so that it cannot be overridden, thereby preventing unauthorized reuse thereof. When locked in this second position, the syringe may be safely disposed of.
One drawback in the design of the Monoject.RTM. syringe is that the locking mechanism must be securely fixed in the second position prior to disposal. This may not always take place, thereby giving the unauthorized user an opportunity to reuse the syringe. In addition, given enough force, the locking mechanism presently employed on the Monoject.RTM. syringe can be overridden, enabling an unauthorized user access to the syringe. If the shield becomes unlocked during or after proper disposal, the risk of accidental needle-stick injury is no different than with the unshielded syringe design. The syringe design of the present invention attempts to resolve these deficiencies.
Other unique syringe designs intended to reduce accidental needle-strike incidents are shown in the following U.S. Patents, the disclosures of which are hereby incorporated herein by reference:
U.S. Pat. No. Re. 33,585, which provides a shielded safety syringe; U.S. Pat. No. 5,125,898, which is directed to a disposable syringe with automatic needle retraction; U.S. Pat. No. 5,122,117, which teaches and claims a component mixing syringe; U.S. Pat. No. 5,108,378, directed to a disposable self-shielding hypodermic syringe; U.S. Pat. No. 5,106,380, which claims a shielded syringe; U.S. Pat. No. 5,084,019, which claims a syringe with means to destroy and safely store the cannula; U.S. Pat. No. 5,084,018, claiming safety syringes; U.S. Pat. No. 5,066,281, directed to a disposable syringe apparatus with retractable needle, locking device and cap device; U.S. Pat. No. 5,047,017, directed to a syringe which will render itself useless after one drug shot and which is tamperproof; U.S. Pat. No. 5,035,703, which claims a disposable syringe needle and scalpel holder; U.S. Pat. No. 5,013,299, which claims a syringe resheathing device; U.S. Pat. No. 5,002,533, directed to a syringe guard apparatus; U.S. Pat. No. 5,000,738, which claims a protective syringe with frangible barrel; U.S. Pat. No. 5,000,736, which is directed to a disposable syringe with automatic needle retraction; U.S. Pat. No. 4,986,817, which claims a hypodermic syringe sheath holder and needle guide; U.S. Pat. No. 4,986,813, which claims a disposable hypodermic syringe; U.S. Pat. No. 4,969,454, which claims an emergency percutaneous cricothyrotomy device; U.S. Pat. No. 4,958,622, which claims a hypodermic syringe for taking and transporting a specimen; U.S. Pat. No. 4,950,242, which is directed to a hypodermic needle cover and assembly therewith; U.S. Pat. No. 4,950,241, which claims a disposable syringe; U.S. Pat. No. 4,944,723, which describes a universal disposable safety syringe system; U.S. Pat. No. 4,915,702. which claims a shielded safety syringe; U.S. Pat. No. 4,904,243, which is directed to a device for self-administration of drugs or the like; U.S. Pat. No. 4,894,054, which claims a preloaded automatic disposable syringe; U.S. Pat. No. 4,892,523, which is directed to a shielded safety syringe; U.S. Pat. No. 4,861,338, which claims a safety syringe; U.S. Pat. No. 4,838,870, which is directed to a removable needle attachment having a detachable needle; U.S. Pat. No. 4,834,717, which claims a disposable, pre-sterilizable syringe for a prefilled medication cartridge; U.S. Pat. No. 4,826,489, directed to a disposable safety syringe having means for retracting its needle cannula into its medication cartridge; U.S. Pat. No. 4,826,484, which claims a disease control syringe having a retractable needle; U.S. Pat. No. 4,820,275, which is directed to a retractable needle syringe with integral spring; U.S. Pat. No. 4,808,169, which claims a disposable safety syringe having means for retracting its needle cannula into its medication cartridge; U.S. Pat. No. 4,804,370, which is directed to a disease control syringe having a retractable needle; U.S. Pat. No. 4,790,827, which claims a shielded safety syringe; U.S. Pat. No. 4,786,281, which is directed to a device for connecting one end of a liquid medicament delivery cannula to an apparatus for connecting a syringe to a vial containing the medicament; U.S. Pat. No. 4,781,701, which claims a syringe for medical purposes; U.S. Pat. No. 4,770,655, which is directed to a disease control syringe having a retractable needle; U.S. Pat. No. 4,767,413, which claims a dental syringe having an automatically retractable needle; U.S. Pat. No. 4,758,231, directed to a shielded safety syringe; U.S. Pat. No. 4,747,830, which claims an anti-stick contagion free disposable hypodermic safety syringe; U.S. Pat. No. 4,717,386, which is directed to a safety device for a needle; U.S. Pat. No. 4,710,170, which claims an anti-needle strike and anti-drug abuse syringe; U.S. Pat. No. 4,356,822, which claims a syringe assembly; U.S. Pat. No. 4,186,783, which is entitled Chemical injector; U.S. Pat. No. 3,727,613, entitled Safety Catheter Placement Assembly; and U.S. Pat. No. 3,669,111 entitled Automatic Retracting Hypodermic Syringe, among others.
Another safety syringe design is shown in copending application Ser. No. 07/787,915, filed Nov. 6, 1991, now U.S. Pat. No. 5,188,601. The disclosure of this application is hereby incorporated herein by reference.
The recitation of patented safety syringes provided above is not intended as being a complete listing of all safety syringes patented in the United States over the last twenty (20) years. It is merely provided to show the great interest in this art area, and to provide a basis of the numerous designs of such syringes wherein the improvements of the type described and claimed herein can be employed.